Tuesday, June 23, 2009

White is Green

In keeping with my Use Paper and Save Trees post, I came across this article today. It talks about how Obama's energy secretary, Steven Chu, wants to "paint the world white" to fight global warming. In fact he feels so strongly, he says "I think you should regulate." Does this make sense?

At first glance, this is a stupid idea. The average albedo of the Earth is 0.367. Pavement has an albedo of 0.05 to 0.4, and gets lighter as it ages. So one might consider 0.1 a pessimistic average albedo for paving. Using all light colored paving (0.4, rather than 0.05) would reflect about 35% more light. How would that change the average albedo of the Earth? Barely at all. The same argument can be made for roofs.

However, let's consider some other aspects of the change. The heaviest concentration of roofs and paving will be in urban areas, where the heat from all those buildings and roads has a disastrous effect on local climate and comfort. Certainly making buildings and roads a lighter color would improve life for city dwellers.

But that's just the start of it. Lighter colored buildings will absorb less heat, requiring less energy for air conditioning. Lighter colored roads will require less lighting at night which will also save energy. Saving 35% off an air conditioning bill is a significant change. Heating and air conditioning is the second largest consumer of energy in this country (after automobiles).

So the science is sound (as the native Americans of the American Southwest or the inhabitants of Saharan Africa or the Mediterranean could tell you). Light colored buildings and road make sense. Should this be a matter for federal regulation, however? There I have to disagree. Simply publicizing the cost savings should be enough for businesses and municipalities to want to take part. If needed, local building codes could be changed. Putting federal regulation in place is just a grandstanding waste of my money. So I guess we'll be regulatin' then.

What do you think?


But in the winter...it holds the heat in...making it warmer...so we use less heating oil....

Yes. Furthermore, the lighter colors will cause snow to melt slower, which will hold in even more heat. OTOH, most of these materials are naturally dark, so we're talking paint, with all of its VOCs and other environmental impact.

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